Virtually all of the ten billion broiler chickens which are currently produced annually in the United States are raised from one day of age until ready for processing in confined houses under conditions which will assure that the quality of the resulting carcass is as free as possible from defects or blemishes. The presence of abnormalities can result in parts or all of the affected carcass being down graded or condemned as being unfit for human consumption which results in substantial losses both to the poultry producer and the consumer.
In raising poultry such as chickens from brooder chick size to broiler size, which normally requires a growing period of about six to ten weeks, the birds must be protected and raised under conditions which will prevent them from injuring themselves so as to degrade their appearance and hence lower their quality. The higher the quality, the higher the price to the grower.
In the latter part of the growing cycle, the birds develop rapidly and gain considerable weight. During this period the birds spend a considerable amount of time resting on their breasts rather than standing in an upright position. If the support surface under the birds is hard, such as a wire support base in a cage or a floor with no cushioning material such as wood shavings or sawdust, considerable wear is imparted to the breasts of the birds during their normal activities. This wear to the breasts will quickly irritate the bursa of the sternum and eventually result in the development of large fluid containing blisters.
While poultry growers have long recognized this problem and the disastrous results in terms of the birds being down graded or condemned, an effective and inexpensive solution to their problem does not presently exist in the art of poultry growing. Growers have long appreciated that poultry cannot be raised successfully to maturity in cages on a commercial scale because of the inability to provide a support which will not produce deformities in the birds. In order to circumvent this problem, poultry are usually raised in large brooder pens which utilize wood shavings or sawdust or a similar type of material as a support. While this approach has been reasonably effective for rearing poultry in brooder pens, regular refurbishment of the support material is required because the birds eat and/or compact the material such that a hard surface crust will form. The support material must then be cultivated or otherwise broken up or new material added to avoid the deleterious results of the hard surface crust. Moreover, as the poultry droppings accumulate in the support material, in a comparatively short time it will have to be replaced. Of course, sawdust-type of support is satisfactory only in brooder pens and is not practical for use in cages.
One of the earlier designs for commercial raising of chickens is shown in the patent to Scott, Patent No. 734,619. No particular discussion of the chicken support or litter problem is included but several of the problems inherent in raising chickens are discussed. The patent describes the general overall environment for raising poultry.
Moving forward fifty years, the patent to Ratermann, U.S. Pat. No. 2,565,521, describes a stacked series of chicken pens designed to house laying chickens. The cage is completely of wire screen and there is no concern whatsoever for raising a chicken for meat quality. The chicken droppings fall through the screen mesh onto a conveyor belt, with one conveyor belt being located below each level of chicken cages. In modern egg farms there is no conveyor belt for each layer of pens but otherwise the system is not greatly changed in general concept.
The patent to Marr, U.S. Pat. No. 3,726,255, recognizes the problem of breast blisters and the like in conventional cages and has attempted to solve the problem by a unitary resilient mat disposed on the floor of a standard cage. This prevents the bird from direct contact with the hard surface of the floor. Chicken droppings, feathers, etc. are intended to fall through the apertures in the resilient mat. To be effective this unitary mat must have its apertures in vertical register with similar apertures in the floor of the cage, otherwise the droppings will tend to collect in blocked apertures. There is still the problem that droppings will not necessarily fall in an aperture and after a period of time it will be necessary to clean the cage to remove the droppings from the horizontal surfaces of the mat.
A second patent recognizing the problem of blisters on the keel bursa of the poultry is in the patent to Stevenson and Johnston (Johnston being the inventor of this invention), U.S. Pat. No. 3,771,495. Again the solution suggested by the patent is to use a resilient unit to rest on the floor of the pen and again there are apertures in the resilient member designed to be in register with apertures in the hard floor. The same problem exist in disposing of the animal feces and its unintended collection on the horizontal surface of the resilient covering of the floor.